DE2148457C3 - Use of polymeric binders in aqueous dispersion for the production of building coatings - Google Patents

Description

Emulsion paints and plastic-bound plasters usually adhere well to a wide variety of substrates, such as B. wood, concrete, plaster or cement asbestos. Even on glass and ceramics, the adhesion is sufficient in most cases if the substrate and the coating material are dry. After the coatings are soaked through with moisture, however, the adhesion drops very sharply. This is particularly evident in the case of coatings that are applied to glass, ceramics and glazed substrates and that have been exposed to underwater storage or prolonged rain. The coatings then either peel off by themselves or can be removed from the substrate by the slightest force. The deteriorated wet adhesion also occurs with substrates such as concrete, P \ l7 and cement asbestos. Such substrates, however, are usually rough, so that the deteriorated wet adhesion does not have such a serious effect.

It is also known that plastic plasters produced with aqueous polymer dispersions as binders in the case of dampness in the rain or in the zone of rising damp due to water absorption swell and soften. This increases their resistance to mechanical stress, z. B. by hail, falling rocks or willful attacks lower.

(In GB-PS 9 98 221 building coatings described, which are applied from aqueous solution. These show the decisive disadvantage that they cannot withstand the stress of driving rain.

The invention relates to the use of polymeric binders in an aqueous dispersion, consisting from polymers of vinyl esters, acrylic esters or butadiene-styrene copolymers, the silanol groups Contained in polymerized form, for the production of building fittings.

Surprisingly, the use of the polymer dispersions containing silanol groups results in a greatly improved wet adhesion of the coating compositions. This is particularly important for substrates made of glass, ceramics and glazed material. In addition, it is found that the coating materials hardly swell in the presence of water and only slight softening occurs. Another advantage is μ . that it is only because of the very good adhesion properties of the coating compositions to be used according to the invention that foamed glass building blocks can be coated. So far, the use of such refractory materials for aesthetic reasons ^ was limited, since conventional coating agent had insufficient adhesion and thus not the aesthetic demands sufficient coating was possible.

In general, the polymeric binders used according to the invention are obtained by polymerization of the monomers and optionally oil-soluble comonomers in aqueous dispersions in the presence of unsaturated hydrolyzable organic silicon compounds produced. Customary emulsifiers are used and / or protective colloids and water-soluble radical-forming catalysts and optionally water-soluble ones Monomers as well as polyolefinically unsaturated monomers are used.

The monomers are vinyl esters with straight-chain and branched carboxylic acids having 2 to 18 carbon atoms, preferably 3 to 12 carbon atoms, such as. B. vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl 2-ethylhexoate, vinyl isononate, vinyl stearate, vinyl laurate, vinyl versatate in question. Js ¹ mixtures of different Vinylester can be used. In addition to the vinyl esters, other olefinically unsaturated monomers up to 70% by weight, preferably up to 50% by weight, can also be copolymerized, e.g. B. vinyl halides, for example vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride: olefins preferably with 2-4 carbon atoms such as e.g. B. ethylene, propylene, isobutylene; Mono- and diesters of unsaturated carboxylic acids, such as. B. (Methacrylic acid esters of alcohols with 1-18 carbon atoms, crotonic acid esters, mono- or diesters of maleic acid, fumaric acid, itaconic acid, with alcohols with 1-18 carbon atoms. Ethylene is preferably copolymerized at a pressure of 1-100 atm. Terpolymers can also be used such as vinyl acetate-vinyl chloride-vinyl laurate terpolymers can be used.

The acrylic esters are esters of alcohols with 1 - 18 carbon atoms, such as ethyl acrylate, Propyl acrylate, butyl acrylate, hexyl acrylate, in question. Copolymers too with the above comonomers can be used.

The copolymers of butadiene and styrene contain up to 40% by weight of butadiene.

The polymerized organic silicon compounds are called compounds of the general formula

OR ₂

R-Si-OR ₂ '
OR ₂ "

wherein R is a radical which is olefinically unsaturated in the ω-position. R2, R2 '. R2 "same or different primary or secondary optionally substituted with alkoxy groups Alkyl radicals or alcyl radicals or a maximum of two radicals hydrogen can be used. These Silicon compounds are metered in during the polymerization and hydrolyze to give hydroxy groups Silicon compounds (silanol groups) contained in the polymer.

Suitable hydrolyzable unsaturated organic silicon compounds are mainly compounds whose radical Ri is an (»-unsaturated alkenyl with 1-10 carbon atoms, preferably 2-4 carbon atoms, or an (» -unsaturated carboxylic acid ester of carboxylic acids with up to 4 carbon atoms and alcohols with up to 6 carbon atoms is. As radicals R ₂ ,

Ra ', Rj "come with primary and secondary alkyl radicals up to 10 carbon atoms, preferably up to 4 carbon atoms, or with alkoxy groups, preferably up to 3 carbon atoms, substituted alkyl radicals or acyl radicals with up to 6 carbon atoms, preferably up to 3 carbon atoms. Examples of such compounds are

Vinyltrimethoxysilane, VinyItriäthoxysilan,
Vinyl diethoxysilanol, vinyl ethoxysilanediol,
AllyItriäthoxysilan, VmyItripropoxysilan,
Vinyl triisopropoxy, vinyl tributoxy,
Vinyltriacetoxysilane, trimethylglycol-vinylsilane,
y-methacryloxypropyl-trimethylglycolosilane,
y-acryloxypropyl-triethoxysilane,
y-methacryloxypropyl-trimethoxysilane.

The dispersions produced in this way contain 0.1 to 5% by weight, preferably 0.3-3% by weight, based on Polymeres, on silanol groups and can as such can be used. Corresponding powders redispersed in water can also be used to produce the Building coatings are used.

According to the invention, under building coating agents understood all means that are used in the construction industry to protect buildings embellish, seal, etc. In particular, the polymers containing silanol groups are used as polymeric binders Used for the production of dispersion-based paints and plastic plasters.

Dispersion-based paints mostly consist of

a) 5 to 35 percent by weight of silanol groups Polyvinyl ester, polyacrylic ester or butadiene-styrene copolymer,

b) 5 to 35 percent by weight water,

c) 5 to 55 percent by weight filler,

d) 5 to 30 percent by weight of pigments.

Examples of fillers that can be used are quartz powder, fine quartz sand, kaolin, highly dispersed silica, Feldspar, barite, light spar, potassium carbonate, chalk, dolomite and talc.

Examples of pigments that may be mentioned are titanium dioxide, zinc oxide and zinc sulfide.

The emulsion paints can optionally contain wetting agents in amounts of 0.2-0.6% by weight, based on Fillers, are added. Anionic and nonionic wetting agents are suitable. Most of the time are polyphosphates, such as. B. Sodium hexametaphosphate, naphthalene sulfonates, ammonium and sodium polyacrylic acid salts, used.

Other aids are thickeners. Organic thickeners are used in amounts of 0.01 - I% by weight, based on the total paint used. Examples of such thickeners are Cellulose derivatives, alginates, starch and starch derivatives, as well as polyacrylic acid. Inorganic thickeners are used in amounts of 0.05-2% by weight, based on Total emulsion paint, used, preferably bentonites or hectorite are suitable.

Fungicides are often added to the emulsion paints for preservation. These come in Quantities of 0.01-2% by weight, based on the total emulsion paint, for use. Examples of such fungicides are phenol and krcsol derivatives, mercury and organotin compounds.

Antifoam agents such as silicone oils, Alcohols and hydrocarbons, in amounts of 0.1 to 0.5 percent by weight, based on the total emulsion paint; Solvents and film-forming aids, such as, for example, glycol acetate and polyhydric alcohols in quantities from 0.1 to 5 percent by weight, based on total dispersion; Antifreeze agents such as methanol and Glycol in amounts of 1 to 5 percent by weight, based on total dispersion color, and dyes, such as organic Binding pigments, are added.

Plastic plasters consist of polymer binders, coarse fillers and water. The proportions of the individual components can vary widely, depending on the intended use.

Polymeric binders contain at least 6% by weight. The amount of filler and resin together is at most 90% by weight. The rest consists of water.

As coarse-grained fillers are all granular materials that have sufficient weather resistance have, can be used. Examples of such materials are plastic grains, quartz pieces, and stone materials. Their grain size is often between 0.2 and 5 mm. In some cases, larger grains are used.

Wetting agents, antifreeze agents, fungicides and dyes may be used as auxiliaries. For example, the compounds mentioned above can be used here.

The building coating compositions are produced by the generally known processes, with homogeneous masses can be produced by thorough mixing of the individual components. According to the invention The dispersions used behave in the same way as corresponding ones in the production of the architectural coatings Dispersions without silanol groups, so that tried and tested formulations by the addition of the invention Dispersions to be used changed light Need to become.

example 1
Wet adhesion of emulsion paints

The following procedure was used to test wet adhesion: glass plates with a width of 4 cm and a length of 15 cm were with the to Testing emulsion paint coated with a wet film thickness of 300 μ, a glass fiber fabric with the Dimensions 4 χ 17 cm so laid and rolled in, that 2 cm survived on the narrow side of the glass plate and the tissue again with the to be tested Emulsion paint coated with a wet film thickness of 200 μ.

After a drying time of 7 days in a standard climate (22 ° C / 50% relative humidity) a part the glass plates are placed in water and left under water for 7 days. The test for adhesive strength was carried out by clamping the coated glass fabric and

W) the glass plate in a tensile tester and peeling off the coated glass fabric at an angle of 180 °. The peel strength was measured on 5 test specimens in each case measured and the mean value formed. The emulsion paints to be tested showed a pigment volume

6i centering of 35, 45 and 52.5%, respectively, as they are for Exterior emulsion paints are common. For the production of the emulsion paints, the following were used separately Pastes Usage:

a) Pigment gradient from tables 1.52 kg rutile titanium dioxide,

2.70 kg barium sulfate, grain size up to a maximum of 5 μ jCunststolT- and dispersion

650 ml of a 1% solution of sodium hexa- 5 metaphospiiat

b) Dispersion mixture: The dispersion mixture consisted of 100 g of the plastic dispersion to be tested (50% by weight), 20 g of a 2% solution of a highly viscous hydroxyethyl cellulose io in water and 1 g defoamer (mixture of higher alcohols and hydrocarbons). The A. The proportions of pigment and dispersion mixture for the individual tested The pigment volume concentration can be found in Table I 15. B.

Pigment volume concentration

Peel resistance on glass after 7 days of storage under water
(kg / 4 cm) mean value

Peel strength on cement asbestos after 7 days of storage under water (kg / 4 cm) mean value

Table I.

Pigment volume concentration

a) Pigment tendency

(G)

384
439
464

b) dispersion mixture

(G)

403 300 239

20th

25th

In addition to the experiments with glass, the 30th The same experiments were also carried out on fluated cement asbestos panels of the same size. When stored in a dry place and testing for peel strength> the breakage occurred in the film, with wet storage and testing for peel strength the separation took place at the interface between the film and the substrate.

The following plastic dispersions were used (50% by weight solids content):

A: Copolymer of 40

82 wt .-% vinyl acetate and

18% by weight ethylene;
B: Copolymer from

82 wt .-% vinyl acetate and

18 wt% ethylene + 45

1,? 5% by weight vinylsilanol;

(created by hydrolysis of triethoxyvinylsi-

lan during polymerization);
C: Copolymer from

50 wt% styrene + 50

50% by weight of butyl acrylate;
D: copolymer from

50 wt% styrene +

50% by weight of butyl acrylate +

1% by weight vinylsilanol 55

(originated from trimethylglycol vinylsilane); E; Terpolymer from

25% by weight vinyl chloride,

25% by weight vinyl laurate and

50% by weight vinyl acetate; ₆ o

F: Terpolymer from

25 wt% vinyl chloride.

25% by weight vinyl laurate and

50% by weight vinyl acetate +

1.5 wt% vinylsilanol 65

(originated from triethoxyvinylsilane).

The results are given in Table II.

35 below 0.1 1.3 45 below 0.1 1.25 52.5 below 0.1 1.0 35 below 1.8 2.1 45 below 2.1 2.0 52.5 below 2.1 2.1 35 under C} 1.75 45 under Ο, ί 1.80 52.5 below 0.1 1.75 35 below 1.6 2.1 45 below 1.7 2.3 52.5 below 1.6 2.2 35 below 0.1 1.6 45 below 0.1 1.4 52.5 below 0.1 1.3 35 below 1.7 2.0 45 below 1.9 2.1 52.5 below 1.8 2.1

Example 2 Softening of plastic plasters

A plastic plaster was produced according to the following recipe:

150 kg mica with a grain size of 100-500 μ 30 kg dolomite with a grain size of approx. 30 μ

30 kg of rutile titanium dioxide

150 kg barium sulfate, grain size up to a maximum 10μ

100 kg quartz powder, grain size up to approx. 80 μ 140 kg quartz sand, grain size 0.1-0.4 mm 140 kg quartz sand, grain size 0.2-0.6 mm 50 kg of round quartz sand 13-2mm0 0.1 kg sodium hexametaphosphate 2.5 kg organic mercury fungicide 2.5 kg defoamer (mixture of higher Alcohols and hydrocarbons)

31 kg of a 3% methyl cellulose solution

(150OcP)
170 kg plastic dispersion

This plaster was made on floated Asbest cement panels applied with the eaves egg and smoothed. The layer thickness was approx. 2-3 mm. The plates were 7 Days in standard climate (22 ° C / 50% relative humidity) cured and then stored under water. The test for softening is based on DIN 53 153 with the Buchholz indentation test body, although this does not include the conversion to DIN

was made, but only the penetration length of the test specimen was measured in mm. It the same plastic dispersions as in

Example I used. The softening test was carried out after 5, 24, 48, 72 and 96 hours. the Results are given in Table IM.

Table III Softening of synthetic plaster Penetration length in mm of the test specimen

Plastic before after

dispersion water - 5 h 24 h 48 h

storage water storage

72 h 96 h

Λ 0.5 4th 6th 8th 9 10 B. 0.5 2 2 3 4th 4th C. 0 2 4th 4th 4th 4th D. 0 0 0 I. 0 η E. 0 3 7th 9 10 10 F. 0 I. 5 S. 5 4th

Example i

A foamed glass block was coated with a plastic plaster of the recipe according to Example 2. After a drying time of 7 days under standard climatic conditions (22 ^c C / 50%) of the plastic-bound plasters containing the plastic dispersions according to Example 1, tested for adhesion. Some of the glass bricks were stored under water for 7 days after hardening. It was found that all plastic-bound plasters which contained the dispersions to be used according to the invention as binders could not be removed from the glass blocks, while all plastic plasters. which contained the unmodified dispersions as a binder, could be peeled off the substrate without any effort. A difference in adhesive strength was also found for the stones that were stored dry.

Claims (1)

Claim: Use of polymeric binders in aqueous dispersion, consisting of polymers of vinyl esters, acrylic esters or butadiene-styrene copolymers, contain polymerized silanol groups for the production of building coatings.